Children with Attention-Deficit/Hyperactivity Disorder (ADHD) participated in double-blind placebo-controlled randomized trials of stimulants while undergoing anatomic imaging with magnetic resonance imaging (MRI). The four approaches are (1) anatomic imaging with magnetic resonance imaging, (2) neuropharmacology, (3) genetic studies, and (4) neurophysiological investigations. In anatomic studies, girls with ADHD have shown similar basal ganglia and prefrontal brain abnormalities to those seen in our previous study of boys. Subjects also participate in a longitudinal study of brain development. An ongoing follow-up study compares a brain maturation of subjects with good and poor - four years outward. These subjects and others also participate in studies of the genetics of ADHD using family association and affected-sibling designs in collaboration with a multi-center multi-institute consortium. Associated studies document relationship with NET1,and DRD1 and diagnosis of ADHD (1). Longterm followup shows plastic brain changes in relation to good outcome (5). A planned fMRI study of childrens response to single dose of amphetamine is being evaluated.